The present disclosure relates generally to the field of magnetic resonance imaging (MRI). In particular, this disclosure relates to methods and systems for quantitative magnetic resonance imaging (qMRI) using variable flip angle (VFA) techniques.
Magnetic resonance imaging (MRI) is an imaging modality that uses magnetic fields to reconstruct a structure of scanned objects of interest. An MRI scanner includes a magnet for generating a strong static magnetic field, such as a magnetic field in the range of 0.10 Tesla (T) to 7 T, and radio frequency (RF) transceivers for transmitting and/or receiving RF signals. When a body is placed in the generated static magnetic field, the Hydrogen protons within the body align to the magnetic field. An RF pulse is applied in the presence of an oscillating B1 field to tip the spins so that there is a bulk magnetization remaining in the transverse field. When the RF pulse is turned off, the Hydrogen protons return to alignment with the static magnetic field, the longitudinal component increasing and the transverse component decreasing. At a chosen time point, referred to as the sampling time, or echo time, or gradient echo time, data is collected and the received signal is used to reconstruct an image of the scanned body or a part thereof. In the current disclosure, various VFA techniques for reconstructing MR images based on collected MR datasets are described.